Hair color, dyes, and tints do not affect the test results because they contain chemicals, not minerals. However, it is best to wash your hair at least once after applying a tint, dye, or color rinse before cutting a hair sample.
Bleach, highlights, and perms can alter the structure of your hair. So, either cut your hair sample before treatment, or after you have washed your hair five or more times following a lightening, bleaching or perming treatment. The hair tends to re-balance after five washings. For highlights, since they are done on the surface of the hair, you can simply sample a piece of hair that has not been highlighted on the underside of your head.